Central and peripheral contributions of deafferentation-induced norepinephrine increase in the habenula

This work examined the contributions of sympathetic and central noradrenergic (NA) innervation to habenular norepinephrine (NE) increase after partial deafferentation. Adult rats received bilateral stria medullaris lesions and after 4 weeks a second lesion was produced which removed bilaterally the dorsal NA bundle or the superior cervical ganglia. The rats were sacrificed 7 days after the second lesion. The data show that strial lesions induced a non-uniform NE increase in discrete habenular regions, which was contributed to by sympathetic innervation in the medial habenula and by central NA projections in both medial and lateral habenular nuclei. It is suggested that NE increase in response to strial lesions is attributed to differential sprouting of peripheral and central NA innervation in the habenula.